Auto Loan Payoff Calculator
See how adding extra to your monthly auto-loan payment shortens the term and cuts total interest, with the months and dollars you save.
How to use this tool
- Enter your current loan balance.
- Enter the APR and your scheduled monthly payment.
- Enter the extra amount you plan to add each month.
- Read the months and interest you save, and the new payoff date.
- Try different extra amounts to find a comfortable acceleration.
Paying a little extra each month on your car loan can erase months of payments and hundreds in interest. Enter your balance, rate, and an extra amount to see exactly how much you save.
Formula
Each month interest accrues on the balance, then the payment reduces principal:
Interestm = Balancem × r, where r = APR ÷ 12
Balancem+1 = Balancem − (Payment − Interestm)
The loop runs until the balance reaches zero, once at the scheduled payment and once at payment + extra. The difference in months and in summed interest is your savings.
How it works
An auto loan is a simple-interest amortizing loan: interest each month is the outstanding balance times the monthly rate, and whatever is left of your payment knocks down principal. Adding extra to the payment goes straight to principal, so the next month's interest is smaller — a compounding effect that shortens the term faster than the extra dollars alone would suggest.
This calculator runs the full month-by-month amortization twice: once at your scheduled payment and once with the extra added. It reports how many months sooner the loan is gone and how much total interest you avoid. Because interest is front-loaded, extra payments early in the loan save the most.
The model assumes a fixed rate, no prepayment penalty, and that every extra dollar is applied to principal rather than held as a future payment — confirm both with your lender. If your scheduled payment is too small to cover even the monthly interest, the balance would never fall; the tool flags that case so you know the payment itself must rise.
Worked example
$20,000 at 7% APR, $400/mo, adding $100/mo
- Monthly rate r = 7% ÷ 12 = 0.5833%.
- At $400/mo the loan amortizes to zero in 60 months, paying interest along the way.
- At $500/mo ($400 + $100 extra) it pays off in 46 months.
- Months saved = 60 − 46 = 14 months.
- Total interest falls by $874.11 because the balance is retired sooner.
Months saved 14 | Interest saved $874.11 | Payoff 46 months (vs 60 with no extra)
Monthly payment per $10,000 financed, by APR and term
| APR | 36 months | 48 months | 60 months | 72 months |
|---|---|---|---|---|
| 4% | $295.24 | $225.79 | $184.17 | $156.45 |
| 6% | $304.22 | $234.85 | $193.33 | $165.73 |
| 8% | $313.36 | $244.13 | $202.76 | $175.33 |
| 10% | $322.67 | $253.63 | $212.47 | $185.26 |
Key terms
- Principal
- The outstanding balance you still owe, separate from interest charged on it.
- Simple-interest auto loan
- The standard auto-loan structure where interest accrues daily or monthly on the current balance, so extra principal reduces future interest.
- Prepayment penalty
- A fee some lenders charge for paying a loan off early; most auto loans have none, but check your contract.
- Amortization
- The process of paying off a loan with regular payments that cover interest first and then reduce principal.
Frequently asked questions
- Does paying extra on my car loan save money?
- Yes. Extra payments reduce principal immediately, so less interest accrues on the smaller balance. The earlier in the loan you add extra, the more you save because interest is front-loaded.
- Will my lender apply extra payments to principal?
- Usually, but not always automatically. Some lenders apply extra to the next scheduled payment instead. Tell your lender to apply additional amounts to principal, and confirm there's no prepayment penalty.
- Is it better to pay off the car or invest the money?
- If your loan rate is higher than what you'd reliably earn investing, paying off the car wins on a risk-adjusted basis. Lower-rate loans may favor investing — but the guaranteed return of avoiding interest is appealing.